Once upon a time, there was this con man who made chessboards for high-end clients — in this case, a king.

The craftsman was good; his chessboards were better than beautiful. The king, he knew, loved chess. So he hatched a plan to trick the king into handing over an enormous fortune. His plan? He figured, “This king is not too good at math.”

So when the craftsman presented his chessboard at court, he told the king,

“Your Highness, I don’t want money for this. Or jewels. All I want is a little rice.”

“Hmm,” thought the king, who was a con man himself. “I’ve got rice. How much rice?”

“All I want,” said the craftsman, “is for you to put a single grain of rice on the first square, two grains on the second, four on the third, eight on the fourth, and so on and so on and so on, for the full 64 squares.”

“I can do that,” said the king, not thinking. And he ordered his granary to pay the man for the chessboard.

(This story is part of a worksheet in Unit 6 of the CUNY HSE Math Framework.)